Pentitol metabolism of Rhodobacter sphaeroides Si4: purification and characterization of a ribitol dehydrogenase
Kahle, Corinna and Schneider, Karl-Heinz and Giffhorn, Friedrich,, 138, 1277-1281 (1992),
doi = https://doi.org/10.1099/00221287-138-6-1277,
publicationName = Microbiology Society,
issn = 1350-0872,
abstract= The phototrophic bacterium Rhodobacter sphaeroides strain Si4 induced ribitol dehydrogenase (EC 1.1.1.56) when grown on ribitol- or xylitol-containing medium. This ribitol dehydrogenase was purified to apparent homogeneity by ammonium sulphate precipitation, affinity chromatography on Procion red, and chromatography on Q-Sepharose. For the native enzyme an isoelectric point of pH 6·1 and an apparent M r of 50000 was determined. SDS-PAGE yielded a single peptide band of M r 25000 suggesting a dimeric enzyme structure. The ribitol dehydrogenase was specific for NAD+ but unspecific as to its polyol substrate. In order of decreasing activity ribitol, xylitol, erythritol, D-glucitol and D-arabitol were oxidized. The pH optimum of substrate oxidation was 10, and that of substrate reduction was 6·5. The equilibrium constant of the interconversion of ribitol to D-ribulose was determined to be 0·33 nM at pH 7·0 and 25 °C. The K m-values determined for ribitol, ribulose, xylitol and NAD+ (in the presence of ribitol) were 6·3, 12·5, 77 and 0·077 mM, respectively. Because of the favourable K m for ribitol, a method for quantitative ribitol determination was elaborated.,
language=,
type=